Cape Cod Communities to Address Nitrogen Pollution

By ecoRI News staff

Fieldwork has begun in the communities of Barnstable, Dennis, Falmouth, Mashpee and Orleans on a project that may help reduce harmful levels of nitrogen and other nutrients from flowing into Cape Cod waters.

The lessons learned from this pilot project, being funded by the Environmental Protection Agency (EPA), could be applied to other locations throughout southern New England to determine the most effective means to capture nutrients before they negatively impact bays, ponds, streams or coastal estuaries.

The EPA is investigating innovative treatment technologies to help control the discharge of nitrogen from groundwater to Cape Cod waters. One of these innovative technologies is called a “permeable reactive barrier” (PRB), a technology that may be able to intercept and mitigate nitrogen reaching Cape Cod waters.

The EPA chose sites in the five Cape communities for preliminary investigation to explore their potential as suitable sites for PRB installations.

“EPA is eager to see if this promising, low-cost technology can be applied more widely on the Cape and elsewhere to help solve the problem of nutrient pollution impacting local waters,” said Curt Spalding, regional administrator of EPA’s New England office. “We have experience with PRBs to remediate contaminated groundwater plumes, so we are hopeful that this technique can also help diffuse nutrient pollution.”

A permeable reactive barrier is located below the ground surface, to intercept groundwater plumes and use a variety of substrates, such as vegetable oil or wood chips, to intercept nitrogen as it flows toward surface water. PRBs are usually sited perpendicular to the direction that groundwater is flowing, and can be built as a trench-like design or through a series of injection points. Each site has specific factors that will help the EPA and its partners best determine the type of PRB technology to propose.

The sites undergoing preliminary characterization include: Prince Cove Marina, Barnstable; Vinland Road, Kelley’s Bay, Dennis; Mashpee River Road, Mashpee; Sailfish Drive, Bourne’s Pond, Falmouth; Shorewood Drive, Great Pond, Falmouth; and Lonnie’s Pond, Orleans. Site characterization work is expected to be completed by the end of spring.

Following the initial site investigation, EPA will choose one or more of the most promising sites for more detailed characterization, to determine if it can fully support a PRB design. This full site characterization will yield additional data needed to determine the size, depth, type and placement of a potential PRB.

While a PRB will not be installed through this project, a full design will be made available to the towns. The process will help Cape Cod communities decide if a PRB is a suitable solution for future sites and how to design it effectively.